Oracle update with Web Service

Question

I have a windows service running on IIS5 on a 2000 box. It
runs every two hours and pulls information from an Oracle
9i table. I package this information into an xml Docmument
and use the httpwebrequest to send it to web service
running on another machine. When the windows service
receives a successful send to the other machine it updates
the oracle table. On the second server meanwhile the web
service there takes the xml that was send and updates a
SQL7 table. It records a successfull or failed update to
the sql table and packages up the results(xml) and sends
them back to a web service running on the first machine.
This web service then takes the xml it recieves and
Updates the original Oracle table with a success or
failure. In my code I call the executenonquery and find
that 1 row was updated in the oracle table. I close the
connection and open a new one and pull out the field I
updated and email that result to myself. It shows that the
field was updated. However when I look in the Oracle table
through TOAD, or Quest Central the Table is not updated to
what it should be. The first update from the windows
service worked but the second update from the web service
does not work.
I have used the oledb provider that comes with .net, the microsoft .net provider for Oralce and ODP.NET from Oracle. I have
written the code in the web service to run as a
transaction and as just a straight sql statement. I have
written it to call a stored procedure in Oracle that will
update the table with a commit in the stored procedure. In
all cases my code tells me that the update was successful.
A trace running on Oracle shows my code executing with no
errors. Yet in all cases the Oracle table does not update.
I have since written a second windows service that runs 15
minutes after the first one runs and pulls values from a
temp table and does the updates this way THIS WORKS.
I just want to know why the web service could not update
the table directly. I think that this might be a bug in
either the .net environment or in Oracle. I'm sure both
Microsoft and Oracle will blame each others products but
it would be nice to know why this is happening.
If any other developers run into this problem be warned I
worked on it for three weeks and wrote my code 10 ways to
Sunday and it would not work.
Happy coding people.

Answer 1

Let me understand this correctly. You are trying to update a column value twice. First update goes through but second does not and you don't get any error for the second update. If this is the scenario, it is not supposed to work.
Here is the reason. A column can be updated using Dataset only if the original column value in the database has not been changed. This is to avoid the dirty writes. Since the original value has not been changed for the first update, the column value is actually updated in the database. However, for the second update, since the original column value was changed by the first update, second update does not update the column value.